The food industry uses numerous bacteria, in particular lactic acid bacteria (LAB), in order to improve the taste and the texture of foods but also in order to extend the shelf life of these foods. In the case of the dairy industry, lactic acid bacteria are used intensively in order to bring about the acidification of milk (by fermentation) but also in order to texturize the product into which they are incorporated.
Among the lactic acid bacteria used in the food industry, there can be mentioned the genera Streptococcus, Lactococcus, Lactobacillus, Leuconostoc, Pediococcus and Bifidobacterium. Lactic acid bacteria of these genera are used extensively alone or in combination with other bacteria for the production of food products, in particular fermented products. They are used in particular in the formulation of the ferments used for the production of fermented milks, for example yoghurts. Certain of them play a dominant role in the development of the texture of the fermented product. This characteristic is closely linked to the production of polysaccharides.
Fermented milk drinks, such as e.g. drinking yoghurt, form a substantial and increasing market and often serves as background for functional ingredients as pre- and probiotics. There are significant differences between the texture challenges for the stirred yoghurt segment and the fermented milk drink segment. For fermented milk drinks, a high shear treatment after fermentation is often applied to break down the protein network in order to obtain smooth, homogeneous and drinkable products. However, this process has a dramatic cost on the mouth-feel of the fermented milk drink. This balance between smoothness and homogeneity on one side versus mouthfeel on the other side makes it difficult to obtain the optimal sensory profile. WO 2008/092458 relates to a drinking yoghurt with a casein:whey protein ratio of from 4:96 to 12:88 (w/w) which can be made without the formation of a coagulum after fermentation. By omitting coagulum formation the need of homogenization to break down the casein coagulum can thus be left out.
Lactic acid bacteria cultures currently on the market can typically not induce viscosity which is resistant to high shear treatment. As a consequence, thickeners like e.g. starch are often applied in fermented milk drinks to increase the mouthfeel.
Alternatively, an acceptable level of mouthfeel can be obtained by using full fat milk bases, but as the overall trend is a wish for low fat products with a ‘clean label’, i.e. no addition of stabilizing agents, there is a request for alternative solutions. As a consequence, there is a request for bacterial cultures for low fat fermented milk drinks replacing the effects of starch.
Such cultures must provide shear-resistant texture which can undergo shear treatment (up to e.g. 7 bar back pressure) and still maintain the required mouth-feel in combination with a smooth and homogeneous texture.
A lot of low fat and non-fat dairy products as for example set-type yoghurt have entered the market during the recent years. However, the reduction of the fat level has a great impact on the sensory and physical properties of the yoghurt. One factor that is highly affected is the texture properties. Due to weakening of the yoghurt gel caused by lower content of total solids the liquid phase will separate and form a layer on top of the yoghurt. This is referred to as syneresis and is regarded as a defect in the products. Different steps can be taken to reduce the syneresis as to increase the total solids by adding more protein and/or adding thickening agents as starch and gelatine. However these solutions are not very cost and label friendly. Therefore, a decrease in syneresis caused by the bacteria culture would be optimal and highly desirable.
Accordingly, there is a need for a method for obtaining additional lactic acid bacteria which result in an improved stability which can be measured as reduced sedimentation in drinking yoghurt and reduced syneresis in set-type yoghurt. Such lactic acid bacteria can be used in the production of fermented milk products, such as yoghurt, especially low fat or non-fat dairy products with reduced or no addition of thickeners, such as starch and pectin.